The use of a disposable sleeve (also referred to as a sheath) to cover an endoscope is well known in the art. Flexible endoscopes, such as colonoscopes, are notoriously difficult to clean and disinfect thoroughly, leading to problems of cross-contamination between patients. These problems can be avoided by covering the endoscope with a single-use sleeve, which is discarded after use.
Endoscopes commonly have working channels, running from a proximal port outside the body to a distal port at the distal end of the endoscope. When the distal end of the endoscope is inserted into the body, the working channel may be used, inter alia, to pass a surgical instrument through to the distal end of the endoscope in order to perform a surgical procedure, such as a biopsy. Instruments that are used in this manner become contaminated with biological matter from inside the patient's body. As the instrument is withdrawn from the body, it can spread the contamination to the interior of the working channel and to the proximal port of the endoscope.
Methods for sheathing an endoscope while providing working channels that protect the endoscope from contamination are described, for example, in U.S. Pat. Nos. 4,646,722 and 4,741,326, whose disclosures are incorporated herein by reference. These patents attempt to prevent contamination of the endoscope, either by adding disposable working channels external to the endoscope itself (U.S. Pat. No. 4,646,722) or by adding a disposable liner inside a working channel of the endoscope (U.S. Pat. No. 4,741,326). They do not address the problem, however, of contamination that may be spread to the area around the proximal end of the endoscope as the surgical tool is retracted from the proximal port of the working channel.